[3.14] gh-70273: Document default class bindings in tkinter (GH-152389) (GH-152394)

Note in the Bindings and events section that every widget inherits Tk
class bindings for its standard behavior, where they are documented, and
how to suppress an unwanted one by returning "break" from a callback.
(cherry picked from commit 4fd69ef97a67fc935e0d4f30662f2a1985ba6be9)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

diff --git a/Doc/library/tkinter.rst b/Doc/library/tkinter.rst
index 3f8bd75a9698e10f7fe9f9aab48045bb9930d11b..8c0349921b614f7af2a59fb3cd5015e2ca463625 100644 (file)
--- a/Doc/library/tkinter.rst
+++ b/Doc/library/tkinter.rst
@@ -887,6 +887,20 @@ they are denoted in Tk, which can be useful when referring to the Tk man pages.
 | %d | detail              | %D | delta               |
 +----+---------------------+----+---------------------+
 
+The ``add`` parameter above only affects the bindings you make yourself.
+Every widget also inherits *class bindings*
+that implement its standard behavior --
+for example a :class:`Text` widget binds :kbd:`Control-t`
+to transpose two characters.
+These are described in the bindings section of the widget's Tk man page
+(such as :manpage:`text(3tk)` or :manpage:`entry(3tk)`).
+
+Class bindings are processed separately from your own,
+so binding an event yourself does not replace the default; both run.
+To suppress an unwanted default binding,
+bind the event on the widget
+and return the string ``"break"`` from your callback.
+
 
 The index parameter
 ^^^^^^^^^^^^^^^^^^^